Electrical thermostat.



A. GOLDSTEIN.

ELECTRICAL THERMOSTAT.

APPLICATION FILED MAY 2, 1010.

989,347. Patented Apr. 11, 1911 w i Mwooao 3 mm wl'oz glgflattozmewUNITED OFFICE.

ALBERT GOLDSTEIN, OF NEW YORK, N. Y., ASSIGNOR TO INTERNATIONAL ELECTRICPROTECTION COMPANY, A CORPORATION OF NEW YORK.

ELECTRICAL THERMOSTAT.

Application filed May 2, 1910. Serial No. 558,817.

To all whom it may concern:

Be it known that I, ALBERT GoLns'rEiN, a citizen of the United States,residing at New York, in the county of New York and State of New York,have invented a certain new and useful Improvement in ElectricalThermostat-s, of which the following is a specification.

The invention relates to electrical thermostats of the type in which airexpansion in a closed chamber actuates a diaphragm to close a circuit,which may include any desired translating apparatus.

The invention consists in the construction whereby the instrument ismade highly sensitive to slight changes in surrounding temperature, asmore particularly pointed out in the claims.

In the accompanying drawingFigure-1 is a cross section of my thermostat,and Fig. 2 is a section on the line 0?, m, of Fig. 1.

Similar numbers of reference indicate like parts.

The circular case 1 of the apparatus comprises a base portion 2 and acup portion 3, between which the diaphragm 4 is received and held. Saiddiaphragm is to be made of thin sheet metalpreferably the thinnest sheetcopper procurable-and may be corrugated and provided with a centralcontact boss The base 2 is to be made, preferably of steel, much heavierthan the cup 3, so as to form the chief support of the device. The cup 3is preferably of a metal that is highly conductive of heat, such ascopper, and of as small thickness as will afford the necessary rigidity.The flange of cup 3 has a corrugation 6 which enters a similarcorrugation in the flange of base portion 2. The flange of diaphragm 4is clamped between the base and cup portions, so that when said partsare assembled. a

close air-tight joint between them results. The cup portion 3 may besecured by bending its circumferential edge 7 over the edge of baseportion 2.

Centrally. disposed in base portion 2 is a block 8 of insulatingmaterial which receives an internally threaded metal bushing 9,,theflange 10 of which rests on block 8. Through said bushing, to which onecircuit terminal 12 may be attached. passes the ad justable contactscrew 13. The other circuit terminal 11 is connected to the diaphragmSpecification of Letters Patent.

Patented Apr. 11.. 1911..

4. The chamber .15 into which the contact screw 13 enters, is completelydust-proof, this result being secured by the close joint, alreadydescribed, bet-ween diaphragm and case. In the chamber 16 on the otherside of the diaphragm is a fiat spiral tube 17 open at both ends and atits outer end communicating with an opening in the wall of said chamber.

The operation of the apparatus is as follows: The contact. screw 13 ispreferably adjusted so that its tip comes as close to the contact boss 5on the diaphragm as is possible without touching; but it may be adjustedat any predetermined distance. from said boss, dependent upon theconditions under which it is desired the apparatus shall work. Thetemperature of the air within the cham ber 16 and that of thesurrounding atmosphere is normally equalized through the tube 17, sothat there is no danger of the apparatus being set in operation and afalse alarm consequently given by reason of any gradual changes often'iperature in the surroundings. Should, however. a quick rise takeplaccas in the case of fire-the heat is rapidly conducted through thethin walls of chamber 16 and expands the air therein. This air cannotquickly escape from said chamber, because it is retarded by the longspiral tube 17 which is purposely made fiat so as to present a largeinterior surface and corresponding skin friction. Hence the air impulseis communicated to thediaphragm and moves it instantly into contact withscrew 13, so closing the circuit. If the screw is set at some greaterdistance from the diaphragm, then there will be a proportionate delay inthe circuit closing movement.

Any suitable device, such as an alarm which it is desired shall operatewhen circuit is established. may be connected to the terminals 11 and12.

I claim:

1. An electrical thermostat comprising a case, a diaphragm therein, acontact piece in proximity to said diaphragm. and a tube open at one endto the atmosphere and communicating at the other end with the interiorof said case: the said tube being of a length proportioned to cause apredetermined frictional impedance to escape of air from said case. I

2. An electrical thermostat comprising a case having an air vent, adiaphragm in In testimony whereof I haveaffixed my said case dividingthe space therein into signature in presence of two Witnesses.

two chambers, a tube open at both ends disposed in one of said chambersand commu- ALBERT GOLDSTEIN' 5 nicating at one end with said vent, and a\Vitnesses:

contact plece in the other chamber in proxim- GERTRUDE T. PORTER,

ity to said diaphragm. MAY T. MGGARRY.

